I ran the following commands I found in a tutorial:

$sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
$ sudo iptables -L

and got

target     prot opt source               destination

ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED

The man page just says that -L "lists the rules in the chain." I understand the first 5 columns—but what about the last? What do these mean?

  • Do: iptables -t nat -L – PersianGulf Mar 14 '14 at 1:24

The last column contains "options". Not every rule has any.

In this case it means the rule does not affect all packets but only those whose connection (keyword: connection tracking) is in one of the states RELATED and ESTABLISHED.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.